Research finds pesticide impairs echolocation ability in bats

Taipei, Jan. 11 (CNA) In the wake of ongoing debate by experts, neonicotinoid pesticide, imidacloprid, has been proven a threat to the survival of bats in Taiwan after last year being confirmed as harmful to bees by the Environmental Protection Agency of the United States.

A research team headed by Wu Chung-hsin (吳忠信), professor in life sciences at National Taiwan Normal University, found that bats feeding on imidacloprid-tainted insects were unable to fly along learned paths, as a reuslt of which they often 'got lost' while out hunting.

With Formosan leafnosed bats as its experimental subject, the team found that bats treated with a low dose of imidacloprid developed neural apopotosis -- a process of programmed cell death -- in the brain, according to Wu.

'The sonogram of ultrasounds emitted by such bats becomes incomplete,' said Wu on Wednesday, discussing research published in Neuroreport, a peer-reviewed scientific journal in the field of neuroscience, in April 2016.

Wu said his team monitored the sonogram with a customer-made flight tracking device, and filmed the track of light emitted from an LED lightbulb attached to the bats.

The data collected indicated that after long-term exposure to imidacloprid the flight patterns of the bats differed from the paths they originally learned.

'What were regular flight paths become disoriented,' Wu said and 'some even lost their ability to catch insects.'

The team found that the toxicity of imidacloprid and high doses of the heavy metal manganese accumulated in the bodies of bats if they fed on pesticide-tainted insects.

'When toxic substances accumulate to a certain level, they damage the bats' neurons and destroy their echolocation system,' said Wu, whose team has researched the echolocation ability of bats in Taiwan for more than two decades.

Wu said the team has recorded a decline in bat populations around Taiwan in recent years, speculating that the phenomenon could be the result of various environmental pollutants.

Bats serve as a 'bio-index,' allowing humans to determine which toxic substances are poisoning the living environment, Wu said, expressing hope the research will alert people to the danger of environmental pollution.

He suggested people reduce pesticide use, curb pollution and learn to live more harmoniously with nature.

Imidacloprid is a broad-spectrum insecticide that works by interfering with the nerve impulses of insects, killing them. It is used to control pests on a large number of agricultural crops.

In recent yeras, however, there have been reports that suggest neonicotinoid pesticides, including imidacloprid, are the cause of bees dying, hives collapsing and plummeting bee populations worldwide.